diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 0ec2913..b15df14 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4838,18 +4838,19 @@
 
 int mbedtls_ssl_get_dtls_srtp_key_material( const mbedtls_ssl_context *ssl,
                                             unsigned char *key,
-                                            size_t *key_len )
+                                            size_t key_buffer_len,
+                                            size_t *olen )
 {
 
     /* check output buffer size */
-    if( *key_len < ssl->dtls_srtp_info.dtls_srtp_keys_len )
+    if( key_buffer_len < ssl->dtls_srtp_info.dtls_srtp_keys_len )
     {
         return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
     }
 
     memcpy( key, ssl->dtls_srtp_info.dtls_srtp_keys,
             ssl->dtls_srtp_info.dtls_srtp_keys_len );
-    *key_len = ssl->dtls_srtp_info.dtls_srtp_keys_len;
+    *olen = ssl->dtls_srtp_info.dtls_srtp_keys_len;
 
     return( 0 );
 }